将XCode输出写入文件[重复]

Question

我希望 XCode 输出（来自 NSLog() 或其他）自动写入应用程序文件夹中的文件。也就是说，我只想把XCode区的全部内容调试成一个文本文件。

我看到了一些代码 sn-ps，但它们中的每一个都避免显示到 XCode（这是不可接受的）。我只想将调试文本复制到文件中...有没有办法做到这一点？

EDIT 1（在尝试了 Clement 的回答之后）：

我得到一个链接器错误：

EDIT 2（我如何实现克莱门特的回答）：

我创建了一个名为 LogHelper 的新类：

LogHelper.h：

#define NSLog(args...) _Log(@"DEBUG ", __FILE__,__LINE__,__PRETTY_FUNCTION__,args);
@interface MyCustomLog : NSObject
void _Log(NSString *prefix, const char *file, int lineNumber, const char *funcName, NSString *format,...);
@end

LogHelper.m：

#import "LogHelper.h"

@implementation MyCustomLog : NSObject

void append(NSString *msg){
    // get path to Documents/somefile.txt
    NSArray *paths = NSSearchPathForDirectoriesInDomains(NSDocumentDirectory, NSUserDomainMask, YES);
    NSString *documentsDirectory = [paths objectAtIndex:0];
    NSString *path = [documentsDirectory stringByAppendingPathComponent:@"myCustomLog.txt"];
    // create if needed
    if (![[NSFileManager defaultManager] fileExistsAtPath:path]){
        fprintf(stderr,"Creating file at %s",[path UTF8String]);
        [[NSData data] writeToFile:path atomically:YES];
    }
    // append
    NSFileHandle *handle = [NSFileHandle fileHandleForWritingAtPath:path];
    [handle truncateFileAtOffset:[handle seekToEndOfFile]];
    [handle writeData:[msg dataUsingEncoding:NSUTF8StringEncoding]];
    [handle closeFile];
}

void _Log(NSString *prefix, const char *file, int lineNumber, const char *funcName, NSString *format,...) {
    va_list ap;
    va_start (ap, format);
    format = [format stringByAppendingString:@"\n"];
    NSString *msg = [[NSString alloc] initWithFormat:[NSString stringWithFormat:@"%@",format] arguments:ap];
    va_end (ap);
    fprintf(stderr,"%s%50s:%3d - %s",[prefix UTF8String], funcName, lineNumber, [msg UTF8String]);
    append(msg);
}
@end

我在myApplication-Prefix.pch 中添加了#import "LogHelper.h"。

EDIT 3（我找到了解决方案）：

• 我设置了一个名为“runningFromXCode”(follow this link to see how to do it) 的环境变量，以在应用从 XCode 运行时保持调试文本显示在控制台中；

• 我把这段代码写进了application:didFinishLaunchingWithOptions:方法（source）：

  if (getenv("runningFromXCode") == NULL){
      NSArray *allPaths = NSSearchPathForDirectoriesInDomains(NSDocumentDirectory, NSUserDomainMask, YES);
      NSString *documentsDirectory = [allPaths objectAtIndex:0];
      NSString *pathForLog = [documentsDirectory stringByAppendingPathComponent:@"log.txt"];
  
      freopen([pathForLog cStringUsingEncoding:NSASCIIStringEncoding],"a+",stderr);
  }
  

Answer 1

#define NSLog(args...) _Log(@"DEBUG ", __FILE__,__LINE__,__PRETTY_FUNCTION__,args);
    @interface MyCustomLog : NSObject
    void _Log(NSString *prefix, const char *file, int lineNumber, const char *funcName, NSString *format,...);
    @end

    @implementation MyCustomLog
    void append(NSString *msg){
        // get path to Documents/somefile.txt
        NSArray *paths = NSSearchPathForDirectoriesInDomains(NSDocumentDirectory, NSUserDomainMask, YES);
        NSString *documentsDirectory = [paths objectAtIndex:0];
        NSString *path = [documentsDirectory stringByAppendingPathComponent:@"myCustomLog.txt"];
        // create if needed
        if (![[NSFileManager defaultManager] fileExistsAtPath:path]){
            fprintf(stderr,"Creating file at %s",[path UTF8String]);
            [[NSData data] writeToFile:path atomically:YES];
        }
        // append
        NSFileHandle *handle = [NSFileHandle fileHandleForWritingAtPath:path];
        [handle truncateFileAtOffset:[handle seekToEndOfFile]];
        [handle writeData:[msg dataUsingEncoding:NSUTF8StringEncoding]];
        [handle closeFile];
    }

    void _Log(NSString *prefix, const char *file, int lineNumber, const char *funcName, NSString *format,...) {
        va_list ap;
        va_start (ap, format);
        format = [format stringByAppendingString:@"\n"];
        NSString *msg = [[NSString alloc] initWithFormat:[NSString stringWithFormat:@"%@",format] arguments:ap];
        va_end (ap);
        fprintf(stderr,"%s%50s:%3d - %s",[prefix UTF8String], funcName, lineNumber, [msg UTF8String]);
        append(msg);
    }
    @end

stackoverflow.com/questions/7271528/how-to-nslog-into-a-file